1988 Vol.6

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NONLINEARITY OF DIELECTRIC RESPONSE IN KTaO3 CERAMIC AT LOW TEMPERATURE CHEN ZHIXIONG, WANG LI, L. E. CROSS Journal of Applied Sciences    1988, 6 (1): 1-5.   Abstract （290）      PDF（pc） （336KB）（70）       Knowledge map    Save KTaO3 ceramic with excellent dielectric properties has been made by hot isostatic pressing (HIP). In order to study the nonlinear properties of KTaO3 ceramic at low temperature, we measured the electric-field dependence of dielectric constant under bias field up to 16 kV/cm and between temperatures from 4.2 K to 100K. It was found that dielectric constant depends on the bias field at temperatures below 60K and the nonlinearity of dielectric response rises strikingly with decreasing temperature. It is related to the incipient ferro-electricity of KTaO3 ceramic at low temperature. We evaluated the values for nonlinear dielectric response coefficients of KTaO3 ceramic while the Devonshire model was used to fit the experimental data. The values were compared with that of the nonlinear dielectric response cofficients of KTaO3 single crystal which had previously been obtained by both measuring dielectric constants and the phonon frequencies of transverse optical modes in the presense of bias fields. Related Articles | Metrics | Comments（0）

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REGULATION AND CONTROL OF MOLECULAR PARAMETERS OF TELECHELIC POLYMERS YAN DEYUE, WANG GONGSHAN, TANG WEIFONG Journal of Applied Sciences    1988, 6 (1): 6-11.   Abstract （343）      PDF（pc） （321KB）（78）       Knowledge map    Save Telechelic polymers are synthesized via bi-functional living polymerization Initiated mainly by the adduct of sec-butyl lithium and m-diisopropenylbenzene. On the basis of the nonsteady state theory of kinetics of anionic polymerization, a method is established, with which the molecular weight distribution and other molecular parameters of the resultant polymer can be calculated from the reaction condition. Several examples of numerical computation are given, the data tabulated and the curves drawn illustrat the relationship between the molecular parameters and monomer conversion. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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ON POLYMERIZATION KINETICS AND CHARACTERISTICSOF N-VINYL PYRROLIDONE AND METHYLMETHACRYLATE BY FTIR RUAN ZHU, SUN YISHI, FU ZENGLI Journal of Applied Sciences    1988, 6 (1): 12-17.   Abstract （396）      PDF（pc） （375KB）（124）       Knowledge map    Save The copolymerization process of a definite composition of N-vinyl pyrrolidone and methyl methacrylate was tracked by Fourier Transfer Infrared Spectrometer at different temperatures and different concentrations of crosslinking agent and initiator. The copolymerization kinetics and characteristics were studied. A reliable information for optimizing copolymerization technology is presented. The cause of improving transparency of the formed copolymer by adding a small amount of crosslinking agent was discussed. Related Articles | Metrics | Comments（0）

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KALESKI BUSINESS CYCLE MODEL AND ITS REFORM FAN CHONGHUI, ZHANG YIMIN Journal of Applied Sciences    1988, 6 (1): 18-25.   Abstract （449）      PDF（pc） （477KB）（93）       Knowledge map    Save Introducing investment decision equation to improve dynamic behaviour 19 proposed by authors[1]. Based on the proposal, we discuss the necessity of further reform of Kaleski business cycle in order that the result of theoretical analysis coincides with the actual expanded reproduction process of capitalism. We also study the measures of improving dynamic behaviour of the model. In the analysis of discrete system with time delay, Z-transform is utilized, some numerical examples calculated, and the trouble caused by solving transcendental equation is avoided. As the order of characteristic equation becomes higher, the method proposed in this paper shows better its advantages. And microcomputers are found to be the suitable tools for researching dynamic problems. The wrong theoreticle solution of Kaleski model is found out and corrected in this paper. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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OBSERVATION AND ANALYSIS OF THE NOISE DUE TO BIREFRINGENCE MODULATI ON IN FIBER-OPTIC GYROSCOPE PENG GANGDING, HUANG SHANGYUAN, LIN ZONGQI Journal of Applied Sciences    1988, 6 (1): 26-31.   Abstract （362）      PDF（pc） （423KB）（83）       Knowledge map    Save The noise due to the birefringence modulation of a nonideal phase modulator in a fiber-optic gyroscope is investigated. It is found that this noise contributes largely to long term bias drift of the system, and that the phase of this noise has a definite π/2 relation with that of the rotation signal. Theoretical analysis based on the Jones Matrix representation coincides quite well with the experimental results. Measures to reduce the birefringence modulation noise are discussed. Related Articles | Metrics | Comments（0）

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ON A FORMAL SOLUTION OF DUAL INTEGRAL EQUATION SYSTEM IN MEASUREMENT OF SEMICONDUCTORS DAI XIANXI, WANG CHANGPING, LI HONGPANG, HUANG JINGYI Journal of Applied Sciences    1988, 6 (1): 32-39.   Abstract （317）      PDF（pc） （424KB）（63）       Knowledge map    Save In this paper a dual integral equation system in the measurement of semiconductors is suggested. The system is decoupled to be an equation of double integral by an integral transformation. According to Schlömilch theorem, the 2-dimensional problem is reduced to be a one dimensional Fredholm equation. An exact formal solution is obtained and a criterion is suggested to prove the uniqueness of the formal solution. In addition, the relation between the current and transformation function and explicit expression of solution for small r0 are also derived. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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A STUDY ON MICROWAVE APEXCARDIOGRAPHY BEI TIANZHEN, ZHUANG GENSHEN Journal of Applied Sciences    1988, 6 (1): 40-43.   Abstract （429）      PDF（pc） （263KB）（68）       Knowledge map    Save A microwave technique for recording apexcardiograms is reported. A microwave epexcardiography can detect changes in reflected microwaves caused by movement of the chest wall in response to left-ventricle activity. It has the unique advantage of not requiring any mechanical contact with the subject. Results show that microwave technique is useful for delineating the tine structure in the precordial movement and checking up the heart disease. Related Articles | Metrics | Comments（0）

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CURVE RESOLUTION FOR X-RAY PHOTOELECTRON CORE LEVEL SPECTRA XU ZHIZHONG Journal of Applied Sciences    1988, 6 (1): 44-48.   Abstract （348）      PDF（pc） （299KB）（63）       Knowledge map    Save The non-linear least square algorithm proposed by Brown and Dennis has been applied to the procedure of curve resolution for the X-ray photoelectron core level spectra, and satisfying result has been obtained. Some examples performed with this method are shown in this article. Related Articles | Metrics | Comments（0）

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AES XPS AND UPS STUDIES OF THE INTERREACTION OF OXYGEN AND IMPREGNATED DISPENSER CATHODES CHEN DESEN Journal of Applied Sciences    1988, 6 (1): 49-54.   Abstract （376）      PDF（pc） （406KB）（76）       Knowledge map    Save We have performed AES, XPS and UPS measurements of Type S and Type M tungsten dispenser cathodes as well as a model surface consisting of a barium monolayer on a tungsten strip in various stages of oxidation. The results indicate the presence of considerable difference between the Type S and Type M cathodes. It was found that Type M cathode is Ba-O-W system, while Type S cathode seems to be partial barium and partial barium oxide and oxygen coadsobed on tungsten. The oxygen may induce change of chemical state of surface barium and substrate tungsten, and change work function and emissive ability of cathodes. The barium layer in Type M cathode appears to be more insensitive to oxidation as indicated by core level changes tham that in the Type S cathode. The valence band structure is also less sensitive to oxygen than Type S cathode. The tungsten related features are more sensitive to oxygen compared to osmium. Related Articles | Metrics | Comments（0）

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THE STUDY ON EXTINCTION SPECTRA DUE TC PRECIPITATES IN Hg1-xCdxTe BY Mie SCATTERING QIAN DINGRONG Journal of Applied Sciences    1988, 6 (1): 55-61.   Abstract （290）      PDF（pc） （422KB）（83）       Knowledge map    Save Complex dielectrical constants have been calculated for Te, HgTe and Hg1-xCdxTe according to the classical theory. The aerosol model has been applied to take into account the extinction of light due to the precipitates of Te and HgTe in Hg1-xCdxTe, and the extinction spectra resulted from the precipitates with different radii have then been evaluated using Mie scattering theory. Related Articles | Metrics | Comments（0）

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A STRICT CALCULATION OF THE DEPTHDISTRIBUTION FUNCTION ϕ(ρz) OF X-RAY BY MONTECARLO SIMULATION HE YANCAI, CAO LIQUN, CHEN JIAGUANG Journal of Applied Sciences    1988, 6 (1): 62-66.   Abstract （354）      PDF（pc） （336KB）（78）       Knowledge map    Save The differences of the electron scatterings in various solids were considered in claculating X-ray distribution functions in isolated films using Monte Carlo simulation. The integrated values of the forty common elements are given in this paper. Related Articles | Metrics | Comments（0）

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THE EXTREME VALUE CONTROLLING BY DERIVATIONWITH RESPECT TO TIME AND ITS APPLICATIONTO X-RAY DIFFRACTION TOPOGRAPHY LU ZHIPING Journal of Applied Sciences    1988, 6 (1): 67-73.   Abstract （389）      PDF（pc） （1316KB）（67）       Knowledge map    Save The automatic following system of Bragg angle was set up in terms of the extreme value controlling by derivation with respect to time. The relative errors are within ±0.05. We performed some experiments in X-ray topography of sapphire and synthetic quartz and obtained quite good results. Related Articles | Metrics | Comments（0）

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THE EFFECT OF SUBSTRATE ORIENTED ON SiGROWTH RATE IN CVD PROCESS BY SILANE PYROLYSIS ZHANG XIKANG, GU LONGDAO Journal of Applied Sciences    1988, 6 (1): 74-77.   Abstract （447）      PDF（pc） （274KB）（73）       Knowledge map    Save In CVD process by silane pyrolysis, the growth rates of silicon are independent on the orientation and material of substrates. Identical activation energy for growth is obtained for different orientations. It is believed that the silicon growth is carried out by the diffusion of the homogeneous reaction products towards the substrate and the accumulation on it. Related Articles | Metrics | Comments（0）

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INTERFACIAL REACTIONS AND CHARACTERISTICS OF Pt-Si SYSTEM COMPLEX ELECTRODES LI SIYUAN, JIA XIAOTIAN, LI SHOUSONG, SHEN MINGZHI, YIN ZHIPING Journal of Applied Sciences    1988, 6 (1): 78-85.   Abstract （410）      PDF（pc） （3346KB）（75）       Knowledge map    Save In this paper, interfacial reactions and characteristics of multi-layer metal filmson silicon surface such as Al-Ti-Pt-Si, Al-Mo-Pt-Si, Al-Ti-Si etc. are studied systematically. The results of electron spectroscopy analyses, scanning electron microscope and electrical methods of the layered structures are presented, and action mechanisms of these interface effects are discussed. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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A HIGH RESOLUTION TeO2 ACOUSTO-OPTIC DEFLECTOR FOR RAD IO SPECTRAL ANALYSIS HUANG GENGCHEN, ZHAO GUOZHBN, WANG JINGSHENG Journal of Applied Sciences    1988, 6 (1): 86-90.   Abstract （311）      PDF（pc） （2581KB）（66）       Knowledge map    Save A high resolution TeO2 acousto-optical deflector for radio spectral analysis was designed and manufactured according to the principle of off-axis abnormal Bragg diffraction. The theoretical resolution is 19kHz, while in practice, a resolution of 28.5kHz was achieved. The 1dB bandwidth is 22MHz. The deflection is a linear function of input power up to 100mW. An acousto-optical spectrograph with TeO2 deflector was constructed and an excellent result in the observation of dark cloud was obtained. Related Articles | Metrics | Comments（0）

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NEW EMISSION INFRARED BAND (b3∑g+-x3∑u+) IN ALKALI VAPOR OF Li LU YIQUN Journal of Applied Sciences    1988, 6 (1): 91-94.   Abstract （309）      PDF（pc） （213KB）（57）       Knowledge map    Save When we used an overtone (257.25nm) of Ar-Laser (514.5nm) and 457.9nm to pump Li-vapor, we observed a new emission band in Li-vapor. It is believed that the band between lμm to 1.4μm is attributed to the Li2(b3∑g+)-Li2(x3∑u+) transition. Related Articles | Metrics | Comments（0）

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COMPLEX RAY ANALYSIS OF BEAM TRANSMISSION THROUGH GENERALLY-CURVED TWO-DIMENSIONAL RADOMES GAO XIAOJIE Journal of Applied Sciences    1988, 6 (2): 95-102.   Abstract （374）      PDF（pc） （516KB）（87）       Knowledge map    Save Assessment of the radiaton characteristics of certain types of radome-covered antennas poses the problem of transmission of amplitude tapered-aperture fields through a generally-curved dielectric taper. Modeling the amplitude taper by a Gaussian, the incident illumination can be generated by a source at a complex coordinate location. The radome problem is then addressed by tracing complex ray fields from the complex source point through the complex extension of the radome contiguration to the real location of the observer. The complex ray tracing takes into account multiple reflection inside the radome, and the multiple internal reflected complex ray can be combined into a "collective ray" which is weighted with a corrected transmission coefficient. The formulars developed in this study are applicable to generally-curved radomes, though parabolic shell radomes are chosen as the mathematical models for numerical computations. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

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THE MEASUREMENT OF CURVATURE RADⅡ OF SLIGHTLY BENT CRYSTALS BY (nV,-nS)DOUBLE-CRYSTAL DIFFRACTOMETRY CHEN JINGYI, LI RUNSHEN, XU SHUNSHENG Journal of Applied Sciences    1988, 6 (2): 103-108.   Abstract （411）      PDF（pc） （364KB）（80）       Knowledge map    Save The Dumond graphic method is employed in the analysis of crystal curvature radius measurement. A new method for measuring the curvature radius using the (nv,-ns) double-crystal diffractometry with Kα1 spectrum only is proposed. This method is much more sensitive than the usually used (ns,-ns) double-crystal diffractometry with the Ka doublet method. The detectable limit of curvature can be improved about one order of magnitude. The curvature radius of the Si crystal after As+ ion implantation is measured by (nv,-ns) double-crystal diffractometry. Related Articles | Metrics | Comments（0）

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A NEW MODEL OF RAPID INITIAL OXIDATION IN DRY OXYGEN FOR SILICON XU XINZHONG, RUAN GANG Journal of Applied Sciences    1988, 6 (2): 109-116.   Abstract （498）      PDF（pc） （546KB）（138）       Knowledge map    Save A new model of the rapid initial oxidation in dry oxygen for silicon is presented. In this model, both the effects of the change in the interfacial reaction rate coefficient and the enhanced oxygen diffusion on the high, initial oxidation rate of silicon are considered. Using this new model, the trouble and the limitation existing in the so-called fixed positive charge model which was presented by Schafer and Lyon can be avoided. Compared with the oxidation model used in the process simulation program-SUPREM-Ⅲ, our model has a clearer physical meaning. The formula of the model takes the similar form to the linear-parabolic oxidation model, BO it is very suitable for VLSI process simulation. In addition, the model can also explain why there is no rapid initial oxidation of silicon in wet oxygen, and why the initial oxidation rate of nondoped polycrystalline silicon is even larger than that of the <111>-oriented single crystalline silicon. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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A NEW IC WASHED EMITTER TRANSISTOR WITH MICRO-POWER DISSIPATION HONG YUAN, LIU BINGGUO Journal of Applied Sciences    1988, 6 (2): 117-122.   Abstract （428）      PDF（pc） （422KB）（83）       Knowledge map    Save A washed emitter transistor was developed, whose emitter was formed by phosphorus diffusion through a thin layer of thermally grown oxide. Studies were made on DC characteristics, current gain vs. collector current, and current gain vs. temperature. The effects of surface recombination and bandgap narrowing in the emitter on the gain were investigated. The results show that the washed emitter transistor has a uniform gain within the range of five orders of magnitude of IC and can work at a current as low as 1 nA. Compared with the conventional transistors, the minimum working current can be reduced by a factor of 103 and the surface recombination velocity by a factor of 50%, and an increased yield of 20% can be achieved. The gain is less temperature dependent because of lighter bandgap narrowing in the emitter. It can be expected that the power dissipation of ICs will be considerably reduced if the washed emitter transistor is adopted. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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THE MECHANISM ANALYSIS FOR UNIFORM MOTION OF CHAIN WITH VARYING PITCH YAN JINGPING Journal of Applied Sciences    1988, 6 (2): 123-131.   Abstract （388）      PDF（pc） （502KB）（95）       Knowledge map    Save In this paper, the characteristics of the hinged mechanism of a chain with varying pitch, the meshing relation between the chain and sprocket, the regulation of changes in the chain speed, and the determination of main parameters have been studied quantitatively. Related Articles | Metrics | Comments（0） Cited: Baidu(18)

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A STUDY OF SYSTOLIC STRUCTURE FOR CONVOLUTION COMPUTATION LIU CHONGQING, YU RENKANG Journal of Applied Sciences    1988, 6 (2): 132-138.   Abstract （456）      PDF（pc） （493KB）（107）       Knowledge map    Save In this paper, a family of systolic designs for convolution computation classified into two categories, convolution arrays with and without global data communication, is proposed. Systolic architecture, which permits multiple computations for each memory access, can speed up execution of compute-bound problems without increasing I/O requirements. A lot of compute-bound computation problems can be solved by systolic architecture systems, onvolution computation problems can be used in the study of systolic structure. The convolution computation can be implemented efficiently using the systolic architecture systems which are consisted of several single-chip processors served as processing elements. Related Articles | Metrics | Comments（0）

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THEORY AND METHOD FOR EVALUATION OF ROUNDNESS DEVIATION ZHANG HEPING, ZHANG E Journal of Applied Sciences    1988, 6 (2): 139-146.   Abstract （472）      PDF（pc） （492KB）（80）       Knowledge map    Save The problem of roundness is usually discussed in the system of pole coordinate, but the authors deal with this problem in the system of right-angled coordinate and have developed a new method for calculating roundness. The new method ha.s the advantage of high speed and accuracy, and also the program is simple. It is discussed in the paper whether the extreme value of minimum zone evaluation is unique. Some confusing opinions have been clarified, giving the basis for using direct search methods to calculate the minimum zone value of roundness. Related Articles | Metrics | Comments（0）

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SOME NUMERICAL RESULTS OF ONE-DIMENSIONALINVERSION FOR ACOUSTIC WAVESUSING DIFFERENCE METHOD GU GUIDING, ZHANG GUANQUAN Journal of Applied Sciences    1988, 6 (2): 147-155.   Abstract （484）      PDF（pc） （516KB）（83）       Knowledge map    Save In this paper, several difference schemes are considered for the calculation of one-dimensional inversion for acoustic waves, and different kinds of model of acoustic impedance are tested. For continuous acoustic impedance, all the schemes considered are suitable, but for discontinuous impedance, we have to choose a suitable scheme to calculate, when the reflection is strong. In addition, when some noise is artificially added to the multilayer model, the function of the smooth processing is examined to control the variation of acoustic impedance. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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DATA EXTRAPOLATION FOR BANDLIMITED IMAGE SIGNALS PAN JIANQIANG Journal of Applied Sciences    1988, 6 (2): 156-162.   Abstract （336）      PDF（pc） （416KB）（93）       Knowledge map    Save The ill-posedness inherent in the bandlimited signal extrapolation problem can be treated by means of regularization parameters. In this paper, a regularized closed form of the 2-D extrapolation matrix, which is tolerant to noise, is formed by utilizing regularization parameters. Also the realization of the architecture of a two dimensional digital extrapolator is presented. A 2-D recursive Kalman filtering extrapolation algorithm is proposed. Related Articles | Metrics | Comments（0）

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DISCUSSION ABOUT THE EFFECTS OF CRYSTAL LATTICE ON POSITRON ANNIHILATION HUANG XIAOWU, LIN ZIJING, WANG KELIN Journal of Applied Sciences    1988, 6 (2): 163-168.   Abstract （353）      PDF（pc） （364KB）（69）       Knowledge map    Save In this paper, we use Green's function method to study the first-order ladder graphs which include lattice-electron and lattice-positron interaction lines. We calculate some low order Feynman graphs in taking the static limit for electron-positron effective interaction potential, and obtain the formula of partial annihilation rate of the positron for p>pF. Furthermore, we make some numerical calculations, and discuss and compare them with the results of Hede-Carbotte's theory. Related Articles | Metrics | Comments（0）

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THEORY OF PHASE TRANSITION IN THE LAYERED ANTIFERRO-ELECTRIC H2C4O4 ZHANG JINGBO, SUN HEBI, QIN ZIKAI Journal of Applied Sciences    1988, 6 (2): 169-174.   Abstract （429）      PDF（pc） （374KB）（70）       Knowledge map    Save The para-and antiferro-electric phase transition of an H2C4O4 crystal is studied by means of Green's function theory based upon a pseudospin model and by taking into account its layered structure. We derive a first order transition instead of a second order one as concluded by Zinenko with the same model. We also find the change of the order parameter with temperature in better conformity with measurements. Related Articles | Metrics | Comments（0）

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SENSING CHARACTERISTICS OF CO GAS SENSOR OF SnO2 DOPED CeO2 SHBN HESHENG, ZHANG HAN, QU YICAI, SHEN YUSHENG Journal of Applied Sciences    1988, 6 (2): 175-179.   Abstract （441）      PDF（pc） （314KB）（62）       Knowledge map    Save A new type of CO gas sensor of SnO2 doped CeO2 has been made. The sensing characteristics of this sensor have been examined for several gases at different temperatures. The results show that the sensor achieves high sensitivity, excellent selective detection and short response time for CO at a low temperature (115℃). The results are also discussed. Related Articles | Metrics | Comments（0）

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A METHOD OF SIMULATION OF PICTURE WITH COMPUTER QIU YAN Journal of Applied Sciences    1988, 6 (2): 180-184.   Abstract （366）      PDF（pc） （1587KB）（79）       Knowledge map    Save This paper gives a brief method of simulation of picture with mini-computer IBM-PC/XT and matrix printer M2024. Related Articles | Metrics | Comments（0）

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STABILITY AND PHASE-LEAD COMPENSATION OF THE SINGLE TUBE HEAT EXCHANGER CAO GUANYI, H. KANOH Journal of Applied Sciences    1988, 6 (2): 185-188.   Abstract （488）      PDF（pc） （250KB）（81）       Knowledge map    Save Single tube heat exchanger is a typical example of distributed parameter system. The mathematical modes obtained by using partial differential have some properties which do not hold for centralized parameter system, especially due to the existance of essential singular point. The effect of essential singular point on the system stability can be shown by root loci. The system dynamics can be improved by using phase-lead compensation. Related Articles | Metrics | Comments（0）

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THE CHINESE CONTRIBUTION TO THE STUDY OF FIELDS AND WAVES IN MEMORY OF 100TH ANNIVERSARY OF HEINRICH HERTZ DISCOVERY OF ELECTROMAGNETIC WAVES HUANG HUNGCHIA Journal of Applied Sciences    1988, 6 (3): 189-196.   Abstract （332）      PDF（pc） （681KB）（70）       Knowledge map    Save In this paper, the author attempts to review the Chinese contribution to the study of fields and waves, with some special reference to microwaves and optics of the electromagnetic spectrum. Like Maxwell, who accomplished at one blow the theoretical prediction of the existence of electromagetic waves and the identification of light and electromagnetic waves, Hertz discovered experimentally electromagnetic waves and simultaneously, the identity of electromagnetic waves and light. The Chinese are known to have observed the phenomena associated with magnetism, electricity and light, and found their applications, since remote antiquity. Interestingly enough, a long history of two thousand years had elapsed before man began to understand electromagnetism and optics as a unified science at the time of Faraday-Maxwell-Hertz. Some aspects of the Chinese study of fields and waves during recent decades, which are related to the impact of Heinrich Hertz' discovery, are sketched in this paper according to the above theme. Related Articles | Metrics | Comments（0）

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DEVELOPMENT IN THE RESEARCH ON PLASTIC BENDING OF PLATES YU TONGXI, ZHANG LIANGCHI Journal of Applied Sciences    1988, 6 (3): 197-202.   Abstract （405）      PDF（pc） （457KB）（99）       Knowledge map    Save Taking the plastic forming processes of strips and plates, which, are widely applied in modern manufacturing, as background, this paper presents a systematic introduction to the research methods and results on the elastic-plastic bending, springback and wrinkling of plates, made by the authors in recent years. The calculation of the springback of strips and shaped beams after their elastic-plastic bending has been solved completely. The so-called Plastica equations, which describe the large elastic-plastic deflection of flexible stripe, have both theoretical and practical significances. The work on the double-curvature bending and stamping of plates, especially the investigation on the role of membrane forces in the large elastic-plastic deformation of plates, is creative. In the new research field of the elastic-plastic wrinkling of plates during forming processes, energy method and other semi-analytical methods have been developed and successfully applied to solving particular problems; the results obtained are in good agreement with those of the experiment. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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INVERSION OF TWO-DIMENSIONAL ELASTIC WAVE EQUATION WITH TWO VARIABLES WITHIN BORN APPROXIMATION CHENG JIANCHUN, WEI YU Journal of Applied Sciences    1988, 6 (3): 203-208.   Abstract （335）      PDF（pc） （392KB）（94）       Knowledge map    Save In this paper, the P-wave scattering equation of a weak inhomogeneous elastic medium is derived from the elastic wave equation of an isotropic medium. The inversion procedure of P-wave velocity and density distributions of the elastic medium within Born approximation is presented, by using the extrapolating field methods developed in Refs.[1]and[2]. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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ANALYSIS OF SINGULARITIES ARISING IN EM FIELD COMPUTATION HONG WEI Journal of Applied Sciences    1988, 6 (3): 209-214.   Abstract （471）      PDF（pc） （317KB）（140）       Knowledge map    Save Some singularities encountered in the EM field computation are discussed in this paper. Several approaches for dealing with the singularities and their error estimations are given. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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THEORETICAL ANALYSIS FOR THE LATERALMODE OF SECTIONAL CONSTRICTED PLANAR COMPOSITE CAVITY DH LASERS DU GUOTONG, LIU ZHONGYU, GAO DINGSAN Journal of Applied Sciences    1988, 6 (3): 215-221.   Abstract （289）      PDF（pc） （473KB）（72）       Knowledge map    Save In this paper, the theoretical analysis for the improvement of lateral mode selectivity and stability in sectional constricted planar composite cavity lasers (SCP) is made, and the effects of structural parameters on lateral mode selectivity and stability are numerically calculated. The calculated results indicate that, if the structural parameters and the ratio between CDH section and OS section cavity lengths are selected appropriately, the output power of the fundamental lateral mode in SCP lasers is more than 3-4 times that in ridge-guide CDH lasers. Related Articles | Metrics | Comments（0）

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EFFECTS OF SEVERAL KINDS OF ANISOTROPY ONMAGNETIC COERCIVITY Hc OF IRONOXIDES DURING PHASE CHANGES YAO KANYI, YANG ZHIJUN Journal of Applied Sciences    1988, 6 (3): 222-226.   Abstract （403）      PDF（pc） （377KB）（70）       Knowledge map    Save The variations of magnetic coercivity (Hc) during the phase changes between Fe3O4 and γ-Fe2O3 for granular powders and continous thin films are investigated. Whether during the oxidation from Fe3O4 to γ-Fe2O3 or during the reduction from γ-Fe2O3 to Fe3O4, the increases in Hc of the spherical particles and the continous thin films are mainly caused by the stress anisotropy, and the decreases in Hc of the acicular particles are affected with the shape anisotropy related to the changes in particle size. Related Articles | Metrics | Comments（0）

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INVESTIGATION OF OHMIC CONTACT ON HIGH RESISTIVITY SILICON SINGLE CRYSTAL CHEN CUNLI, CHEN ZHENGFU, CHEN YIPING, ZHONG XINQUN Journal of Applied Sciences    1988, 6 (3): 227-232.   Abstract （632）      PDF（pc） （380KB）（143）       Knowledge map    Save By appropriately controlling the surface quality of a silicon wafer and using the electrical sparking technique, high boron-alloy (BAlNiIn) and high phosphorus-alloy (PSbAuIn) can simply be used to make good ohmic contacts on silicon materials of resistivity as high as 20000Ωcm and 4000Ωcm for the P-type and N-type, respectively. Even after 30 times of temperature circulation from 300 K to 77 K, the linear I-V property of the ohmic contacts still remains. The ohmic contact formations and carrier transport characteristics are discussed, based on the current-voltage and specific contact resistance measurements at different temperatures, the ion microprobe analysis, and the calculation of specific contact resistance of metal to silicon as a function of doping concentration. This method has been successfully applied to the measurements of impurity compensation and carrier mobility on high resistivity silicon materials. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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THE ELECTRICAL EFFECTS OF GOLD AND PLATINUM AT THE Si-Al2O3 INTERFACE LI SIYUAN, YIN CHIPING, ZHANG TONGJUN, WANG YUZHEN, JIA XIAOTIAN Journal of Applied Sciences    1988, 6 (3): 233-240.   Abstract （376）      PDF（pc） （549KB）（75）       Knowledge map    Save In this paper, the electrical effects of gold (Au) and platinum (Pt) at the Si-Al2O3 interface and the annealing behaviour of these effects tinder different annealing conditions are studied. The results of the photoelectron spectroscopy of the Si-Al2O3 system are presented also. Further, the action mechanism of Au and Pt at the interface is discussed. Related Articles | Metrics | Comments（0）

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STUDIES IN MAGNETIC PROPERTIES OF NdFeB ALLOYS WITH LOW PURITY NEODYMIUM GONG WEI, WANG YIZHONG, FENG MINYING, WANG ZHENXI, HUANG YONGCHBNG, CAO YONGJING Journal of Applied Sciences    1988, 6 (3): 241-244.   Abstract （379）      PDF（pc） （276KB）（71）       Knowledge map    Save By substituting low purity neodymium for the high purity one, NdFeB permanent magnets of (BH)max=41 MGOe were prepared by powder metallurgy. Several properties of NdFeB alloys were measured by means of x-ray diffraction, the differential thermal analyzer, magnetic balance, extracting sample magnetometer and pulse high magnetic field apparatus respectively. The results show that there is a peak of phase transition at 1439K, and the abnormal phenomenon on the magnetic hysteresis loop at low temperature originates from the conical magneto-crystalline anisotropy of the major phase Nd2Fe14 in the NdFeB alloys. Related Articles | Metrics | Comments（0）

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TEMPERATURE DEPENDENCE OF MAGNETIZATION FOR AMORPHOUS Fe90-xCoxZr10 ALLOYS ZHAN WENSHAN, SHEN BAOGEN, ZHAO JIANGAO, ZHENG XIAONIAN Journal of Applied Sciences    1988, 6 (3): 245-248.   Abstract （337）      PDF（pc） （357KB）（66）       Knowledge map    Save Amorphous Fe90-xCoxZr10(0 ≤ x ≤ 90) alloys were prepared by melt-spinning under argon atmosphere. The temperature dependence of the magnetization of samples was studied. Experiments show that the Curie temperature increases with increasing Co content, but the crystallization temperature decreases. The magnetization σ(RT) at 300K exhibits a maximal value of 161 emu/g. The Co content dependence of σ(RT) is discussed. Related Articles | Metrics | Comments（0）

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